scholarly journals Global Analysis of Bioclimatic Controls on Ecosystem Productivity Using Satellite Observations of Solar-Induced Chlorophyll Fluorescence

2017 ◽  
Vol 9 (6) ◽  
pp. 530 ◽  
Author(s):  
Nima Madani ◽  
John Kimball ◽  
Lucas Jones ◽  
Nicholas Parazoo ◽  
Kaiyu Guan
Keyword(s):  
Chlorophyll Fluorescence ◽  
Global Analysis ◽  
Satellite Observations ◽  
Ecosystem Productivity

scholarly journals Global Energy and Water Budgets in MERRA

2011 ◽  
Vol 24 (22) ◽  
pp. 5721-5739 ◽  
Author(s):  
Michael G. Bosilovich ◽  
Franklin R. Robertson ◽  
Junye Chen
Keyword(s):  
Energy Budget ◽  
Global Analysis ◽  
Satellite Observations ◽  
Shortwave Radiation ◽  
Energy Budgets ◽  
Global Energy ◽  
Significant Research ◽  
Microwave Sounding ◽  
Global Precipitation ◽  
Global Water

Abstract Reanalyses, retrospectively analyzing observations over climatological time scales, represent a merger between satellite observations and models to provide globally continuous data and have improved over several generations. Balancing the earth’s global water and energy budgets has been a focus of research for more than two decades. Models tend to their own climate while remotely sensed observations have had varying degrees of uncertainty. This study evaluates the latest NASA reanalysis, the Modern Era Retrospective-Analysis for Research and Applications (MERRA), from a global water and energy cycles perspective, to place it in context of previous work and demonstrate the strengths and weaknesses. MERRA was configured to provide complete budgets in its output diagnostics, including the incremental analysis update (IAU), the term that represents the observations influence on the analyzed states, alongside the physical flux terms. Precipitation in reanalyses is typically sensitive to the observational analysis. For MERRA, the global mean precipitation bias and spatial variability are more comparable to merged satellite observations [the Global Precipitation and Climatology Project (GPCP) and Climate Prediction Center Merged Analysis of Precipitation (CMAP)] than previous generations of reanalyses. MERRA ocean evaporation also has a much lower value, which is comparable to independently derived estimate datasets. The global energy budget shows that MERRA cloud effects may be generally weak, leading to excess shortwave radiation reaching the ocean surface. Evaluating the MERRA time series of budget terms, a significant change occurs that does not appear to be represented in observations. In 1999, the global analysis increments of water vapor changes sign from negative to positive and primarily lead to more oceanic precipitation. This change is coincident with the beginning of Advanced Microwave Sounding Unit (AMSU) radiance assimilation. Previous and current reanalyses all exhibit some sensitivity to perturbations in the observation record, and this remains a significant research topic for reanalysis development. The effect of the changing observing system is evaluated for MERRA water and energy budget terms.

scholarly journals Satellites Track Chlorophyll Fluorescence to Monitor Drought

Eos ◽  
2016 ◽  
Vol 97 ◽  
Author(s):  
Lily Strelich
Keyword(s):  
Soil Moisture ◽  
Chlorophyll Fluorescence ◽  
Satellite Observations

New satellite observations show connection between solar-induced chlorophyll fluorescence and soil moisture—a key mechanism behind drought onset.

scholarly journals Global Analysis of the Relationship between Reconstructed Solar-Induced Chlorophyll Fluorescence (SIF) and Gross Primary Production (GPP)

2021 ◽  
Vol 13 (14) ◽  
pp. 2824
Author(s):  
Haiqiang Gao ◽  
Shuguang Liu ◽  
Weizhi Lu ◽  
Andrew R. Smith ◽  
Rubén Valbuena ◽  
...  
Keyword(s):  
Chlorophyll Fluorescence ◽  
Primary Production ◽  
Landscape Heterogeneity ◽  
Global Analysis ◽  
Gross Primary Production ◽  
Spatiotemporal Variability ◽  
Spatial And Temporal Scales ◽  
Discriminatory Analysis ◽  
Positive Correlations ◽  
The Relationship

Solar-induced chlorophyll fluorescence (SIF) is increasingly known as an effective proxy for plant photosynthesis, and therefore, has great potential in monitoring gross primary production (GPP). However, the relationship between SIF and GPP remains highly uncertain across space and time. Here, we analyzed the SIF (reconstructed, SIFc)–GPP relationships and their spatiotemporal variability, using GPP estimates from FLUXNET2015 and two spatiotemporally contiguous SIFc datasets (CSIF and GOSIF). The results showed that SIFc had significant positive correlations with GPP at the spatiotemporal scales investigated (p < 0.001). The generally linear SIFc–GPP relationships were substantially affected by spatial and temporal scales and SIFc datasets. The GPP/SIFc slope of the evergreen needleleaf forest (ENF) biome was significantly higher than the slopes of several other biomes (p < 0.05), while the other 11 biomes showed no significant differences in the GPP/SIFc slope between each other (p > 0.05). Therefore, we propose a two-slope scheme to differentiate ENF from non-ENF biome and synopsize spatiotemporal variability of the GPP/SIFc slope. The relative biases were 7.14% and 11.06% in the estimated cumulative GPP across all EC towers, respectively, for GOSIF and CSIF using a two-slope scheme. The significantly higher GPP/SIFc slopes of the ENF biome in the two-slope scheme are intriguing and deserve further study. In addition, there was still considerable dispersion in the comparisons of CSIF/GOSIF and GPP at both site and biome levels, calling for discriminatory analysis backed by higher spatial resolution to systematically address issues related to landscape heterogeneity and mismatch between SIFc pixel and the footprints of flux towers and their impacts on the SIF–GPP relationship.

Satellite observations of cirrus clouds in the lower stratosphere

2020 ◽  
Author(s):  
Ling Zou ◽  
Sabine Griessbach ◽  
Lars Hoffmann ◽  
Bing Gong ◽  
Lunche Wang
Keyword(s):  
Global Analysis ◽  
Average Distance ◽  
Michelson Interferometer ◽  
Drake Passage ◽  
Satellite Observations ◽  
Cirrus Clouds ◽  
Cirrus Cloud ◽  
Middle Latitudes ◽  
Vertical Grid ◽  
The Tropics

&lt;div&gt; &lt;p&gt;While cirrus cloud are frequently observed by ground-based lidars in the lowermost stratosphere, evidence from satellite observations is less conclusive. Following previous studies, we extracted information on stratospheric cirrus clouds from the latest version of Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) data (V4) and the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) data to investigate their global distribution and occurrence frequencies. The detection of stratospheric cirrus with MIPAS is particularly challenging because of the broad field-of-view of the instrument and presented here for the first time.&lt;/p&gt; &lt;p&gt;For the identification of stratospheric cirrus clouds, precise information on both, the cloud top height (CTH) and the tropopause height are crucial. The tropopause heights we derived from ERA-Interim using the WMO criterion for the first thermal tropopause. As tropopause from ERA-Interim show ~0.3km bias with GPS data and CALIPSO data are reported on a ~0.2 km vertical grid, we considered cirrus clouds with CTHs 0.5 km above the tropopause as being stratospheric. We focus on nighttime CALIPSO measurements because of their higher sensitivity. MIPAS measurements are known to overestimate CTHs of optically thick clouds and underestimate the CTHs of optically thin clouds. For the detection of stratospheric cirrus, we started 0.75 km above the tropopause, which is the average CTH overestimation by MIPAS found in previous studies. The comparison with the CALIPSO statistics showed that in the tropics the MIPAS stratospheric cirrus cloud occurrence frequency were slightly larger than for CALIPSO. Assuming that this is due to MIPAS overestimating the CTH, for MIPAS we increased the minimum distance of the CTH to the tropopause until the occurrence frequencies of both measurements agreed.&lt;/p&gt; &lt;p&gt;In the tropics, a four-year mean global analysis of stratospheric cirrus clouds from CALIPSO showed high occurrence frequencies (max. &gt;32%) over the western Pacific Ocean, South Africa, and South America. Stratospheric cirrus clouds were more often detected in December-February than June-August in the tropics. At middle (40-60&amp;#176;) and higher latitudes (&gt;60&amp;#176;), CALIPSO observed about 2% stratospheric cirrus clouds. MIPAS observed about twice as many stratospheric cirrus clouds at northern middle latitudes (&gt;3%) and southern middle latitudes (4%). The maximum differences of nighttime stratospheric cirrus clouds between MIPAS and CALIPSO data were 4-6% over the northern Pacific and 6-8% over the Drake Passage.&lt;/p&gt; &lt;p&gt;Further sensitivity tests with higher average distance to the tropopause for MIPAS resulted in lower occurrence frequencies at middle latitudes. However, they were still larger than the occurrence frequencies derived from CALIPSO data. Hence, we consider the finding of higher stratospheric cirrus cloud occurrence frequencies at middle latitudes by MIPAS as robust. One possible explanation for MIPAS finding more stratospheric cirrus clouds at middle latitudes is that MIPAS is more sensitive towards thin cirrus clouds than CALIPSO (nighttime measurements), because of the satellite limb measurement geometry.&lt;/p&gt; &lt;/div&gt;

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